From having dipped into C++ at a point in my history, it make me think of C++ templates which were also turing complete. Many of skilled people with templates could go overboard into a point where a significant implementation of the program was in an very separated "template metaprogram space" where it was difficult to manage and debug. You would have to read some primary code, then start doing template transforms in your head to figure out what was actually happening. The compile and run-time errors that could pop out were also terrible and long, giant dumps of template syntax trees..

You can get absolutely phenomenal performance, but any major template capability has a high risk of becoming a DSL with terrible debugging ability and slow comprehensibility.

Judicious use could be very nice though...